This story was originally published by our Spanish-language sister site, CityLab Latino.

Nobody knows exactly who they are, or how many people are involved. They don’t have a leader, an organizational structure, or even a spokesperson. All decisions and actions are taken collectively.

But the members of Massa Crítica know how to get things done in the city of Fortaleza, Brazil. The group formed in 2013 as a local chapter of the global bicycle advocacy movement Critical Mass, which is active in more than 300 cities around the world. Most Critical Mass actions involve arranging monthly group rides on city streets as a way to draw attention to biker’s rights. But the Fortaleza group went well beyond that: They began painting guerrilla bike lanes without authorization, at night, along the main avenues and streets of this city of 2.6 million people.

Despite the best efforts of local law enforcement to erase the rogue lanes and crack down on the group, Massa Crítica persisted, even blockading main roads in response. Eventually, the city gave up and yielded to their demands: Today, Fortaleza has more than 200 kilometers of bicycle lanes; prior to Massa Crítica’s efforts, the city had only 60 kilometers.

CityLab Latino corresponded over email with Fortaleza’s Massa Crítica members about how they pulled it off. This interview was conducted in Portuguese and translated into Spanish and English.

What inspired the creation of Critical Mass in Fortaleza?

Protests have taken place in Fortaleza since 2006, as the city completely ignored cyclists for more than 30 years. In 2013, we built a machine to paint bike lanes. About 40 people participated in this project. The movement was born as a horizontal, autonomous, and anti-hierarchical organization. And so it remains until today.

What have been your biggest successes?

Being horizontal, anti-hierarchical, and autonomous in a world that is the opposite of this is a great challenge in itself. We are people who want to change the world and fight against all forms of oppression, but who do not want to gain power. Maintaining that brought us into conflict with local parties, mainly the socialists, who tried at all costs to transform the movement.

“What we want is clear and exposed through our direct actions: We want a city for people and not for the transport of goods.”

Without a doubt, another great victory was to start a bike revolution in the city. There were two crucial moments. The first was the painting of the first cycle track in Avenida Ana Billar in 2013, which was soon made official by the local authorities. The second was two years later, when the city already had more than a hundred kilometers of cycle paths and exclusive tracks for bicycles. That is when the revolution driven by the collective reached its highest point. At that time, Avenida Domingos Olímpio connected two large bike paths in the city and thousands of cyclists passed through it every day. On three occasions, our collective painted cycle lanes, which were erased by the municipality. They argued that it was impossible to make a bicycle path there.

We were not intimidated. We repainted the public bicycle lane twice. We burned tires. We closed the avenue. And finally we protested by blocking the traffic and building a barricade. A month later, the city council developed a project and the track was finally built.

What specific techniques of tactical urbanism worked and which did not?

We can cite three tactics: We made direct actions of high impact, we refused to dialogue with institutions, and we kept our movement anonymous.

We believe in actions that are in the margin of legality, but they are fair. We believe that, if the city council does not do what the citizens require, the people will do it. This puts the state in a difficult situation: Will it criminalize a movement that makes bike lanes, which, despite being illegally built with no permits whatsoever, are there to protect people’s lives?

The tactic of refusing to dialogue with the state or the city council works as a form of pressure. These meetings only serve to postpone actions and demobilize people. What we want is clear and exposed through our direct actions: We want a city for people and not for the transport of goods.

What recommendations would you give other groups of citizens who would like to follow his example?

Get together. Join groups of friends who want to change the world, but do so without a power structure. The struggle must be horizontal, without bosses, and with collective decisions that defy the status quo.

This article is part of a series highlighting the themes of CityLab Paris, a convening of urban leaders.